Substituted benzolybenzoates are known compounds which are usually produced by esterification of the corresponding carboxylic acid with the appropriate alcohol, or by the reaction of the benzoylbenzoic acid chloride with the alcohol. However, such processes are expensive and result in unacceptable yields, primarily because of the difficulty in producing the acid and acid chloride. Also, methods such as azeotropic distillation or addition of acid acceptors are necessary to drive these esterification reactions to completion.
Thus, Beilstein 10, 753 discloses the permangante oxidation of methyl benzophenone to provide benzoylbenzoic acid, a process requiring a large volume of water and resulting in the formation of waste manganese dioxide. Chromic acid oxidation of p-benzoltoluene to provide benzoylbenzoic acid is also disclosed, but this procedure requires a lengthly heating period and produces waste chromic sulfate, a suspected carcinogen. The acid chloride can be made by a Friedel-Crafts reaction of terephthaloyl chloride and benzene in the presence of aluminum trichloride, but the major product of this reaction is dibenzoylbenzene.
Now it has been found in accordance with this invention that butyl-p-benzoylbenzoates can be made by a process which avoids the preparation of the corresponding acid or acid chloride.